1. Field of the Invention
The present invention relates to a projection television, and more particularly, to an optical engine of a projection television which projects an image enlarged by a predetermined magnification and lighting onto a projection television screen. The present application is based on Korean Patent Application No. 2002-62511, which is incorporated herein by reference.
2. Description of the Prior Art
Generally, a projection television is an apparatus for enlarging an image produced in an image producer by a predetermined magnification using a lens and a reflector, and projecting the enlarged image onto a screen in order to have an image sized more than 40 inches. An apparatus used for projecting the image in a projection television is an optical engine and projection televisions can be divided into Cathode Ray Tube (CRT) projection, Liquid-Crystal Display (LCD) projection and Digital Micromirror Device (DMD) projection categorized by the types of the image producer.
The optical engine of a projection television comprises mainly an image producer, a light generator, and a projection apparatus.
The image producer producing a predetermined image uses CRT projection, LCD projection, and DMD projection as described above. CRT projection is used only in high end products since it is capable of reproducing a clear image but large in size, and generally, LCD projection is used. However, recently DMD projection using the DMD, which uses lighting more effectively than the LCD has been developed and distributed.
The light generator is a device for emitting light (hereinafter called illumination) from a light source, such as a lamp, to the image producer and is disposed at one side of the image producer.
The projection apparatus is for enlarging the image produced in the image producer and illumination emitted from the light generator and projecting them onto the screen and disposed in front of the image producer.
Accordingly, as described above for the illumination from the light generator, paths of light in the projection television should illuminate the whole image produced in the image producer. If the illumination from the light generator does not correspond with the image producer, the image projected on the screen 10 has a shadow 13 as shown in FIG. 1.
If a shadow 13 is made on the screen 10, there is a need for adjusting the angle of the mirror in the light generator so that the illumination from the light generator corresponds with the image producer.
In order to adjust the mirror of a conventional light generator, either a mirror holder or height of a supporting portion for supporting the mirror holder needs be adjusted. For adjusting the mirror holder or the height of the supporting portion, the metal mold of the mirror holder or the supporting portion needs to be changed. In addition, although the metal mold of the mirror holder or the supporting portion is changed, some products may have shadows due to tolerance in the mounting of each part forming the optical engine, and in that case the angle of the mirror should be changed individually. Thus, it is too costly to change the reflection angle of the mirror to adjust the path of the illumination from the light generator so that the path of the illumination corresponds with the image producer in manufacturing a projection television.
Furthermore, the screen of the projection television with the mirror adjusted may still have a shadow as the path of the illumination from the light source is deviated by the mirror being moved due to a shock during use. In such a case, the path of the illumination needs to be adjusted by controlling the reflection angle of the mirror by readjusting the mirror holder or the supporting portion, and therefore it is extremely difficult to adjust the illumination path.
Accordingly, there is a need for providing a mirror which can have the reflection angle easily adjusted during manufacturing or use.